Polystyrene MiPolystyrene Microplastics Induce Radiotherapy Resistance in Lung Cancer by Suppressing Ferroptosis through NF-κB Activationcroplastics Induce Radiotherapy Resistance in Lung Cancer by Suppressing Ferroptosis through NF-κB Activation

Aims: Polystyrene microplastics (PS-MPs) are emerging environmental pollutants, but their impact on lung cancer treatment remains unclear. This study investigates how PS-MPs affect radiotherapy efficacy in lung cancer, focusing on their role in ferroptosis regulation and NF-κB pathway activation. Results: PS-MPs were rapidly internalized by lung cancer cells and remained detectable across multiple passages. Exposure to PS-MPs promoted lung cancer cell proliferation, increased mitochondrial length, and elevated Ki67 and c-Myc expression. Following ionizing radiation, PS-MPs significantly attenuated radiation-induced ferroptosis, as evidenced by reduced mitochondrial damage, lipid peroxidation, and GSH depletion. Transcriptomic analysis revealed that PS-MPs activated the NF-κB pathway, leading to increased phosphorylation of IKKβ, IκBα degradation, and enhanced nuclear translocation of NF-κB. In vivo, PS-MPs accumulated in lung tumor-bearing mice, reducing radiotherapy efficacy by increasing tumor volume and weight while decreasing survival rates. Knockdown of NF-κB restored ferroptosis sensitivity and mitigated PS-MPs-induced radioresistance, confirming the NF-κB-dependent inhibition of ferroptosis. Innovation and Conclusion: This study provides the first evidence that PS-MPs impair radiotherapy efficacy in lung cancer by suppressing ferroptosis via NF-κB activation. Unlike previous research focusing on microplastic toxicity in normal tissues, our findings highlight their oncological impact and potential role as an environmental factor influencing cancer therapy resistance. These results emphasize the need for further investigation into microplastics as emerging disruptors of redox homeostasis in oncology and their broader implications for environmental and cancer research.